Unsymmetrical loading on a car like mu-split braking, side wind forces, or unilateral loss of tire pressure results in unexpected yaw disturbances that require yaw stabilization either by the driver ...or by an automatic driver-assist system. The use of two-degrees-of-freedom control architecture known as the model regulator is investigated here as a robust steering controller for such yaw stabilization tasks in a driver-assist system. The yaw stability-enhancing steering controller is designed in the parameter space to satisfy a frequency-domain mixed sensitivity constraint. To evaluate the resulting controller design, a real-time hardware-in-the-loop simulator is developed. Steering tests with and without the controller in this hardware-in-the-loop setup allow the driver to see the effect of the proposed controller to improve vehicle-handling quality. The hardware-in-the-loop simulation setup can also be used for real-time driver-in-the-loop simulation of other vehicle control systems.
Besides lateral instability, one major threat to all ground vehicles, especially SUVs, is the danger of rollover during cornering. A coordination strategy based on fuzzy logic has been devised to ...coordinate the sub-controls; namely, active steering, active differential, active brake and a novel active roll control system. Independent study of each sub-control as well as an analysis of their inter-relationship has been carried out. The coordination strategy is supposed to resolve the conflict among control targets – which are sideslip regulation, yaw rate tracking, lateral acceleration tracking and roll motion control – all of which are to be done while maintaining the driver’s desired longitudinal acceleration. Thus, a compromise must be reached. Vehicle sideslip angle and yaw rate were considered to be the criteria for lateral stability; and a combination of roll angle, roll rate and lateral load transfer was selected as the criterion for roll stability. The results of simulations on two SUV models in CarSim software indicate that the integrated controller can successfully restore vehicles’ stability in critical condition.
This paper is concerned with the design scheme of state feedback controller and parameter optimization method for active stability control of the compressor. Firstly, the linearization system of the ...compressor is proved to be singular, and cannot be used for stability analysis and controller design. Next, aiming at this problem, the center manifold theorem is used to analyze the stability, and the design scheme of active stability controller based on the center manifold theorem is proposed in this paper. After that, a projected gradient method for controller parameter optimization based on parameter sensitivity is proposed. The simulation results show that the proposed method can effectively suppress the instability of the compressor under the initial disturbance. In addition, this method can also simplify the parameter selection of the controller through parameter optimization.
The demand for high-definition surveys within cultural heritage-related projects represents one of the main factors that promoted the use of laser scanning technology and photogrammetry. By measuring ...millions of points within relatively short time periods, terrestrial laser scanners (TLS) allows to researchers to derive complete and very detailed three-dimensional (3D) models of real objects from acquired point clouds. These features drew in recent years the interest of surveyors, engineers, architects, and archaeologists towards the laser scanning technique as an invaluable surveying tool for 3D modeling of sites and artifacts of cultural heritage. A wide variety of objects, such as small pieces of pottery, statues, buildings, and large areas of archaeological sites, have been scanned and modeled for various purposes like preservation, reconstruction, study, and museum exhibitions. However, the use of TLS systems for stability control is still a research field not much investigated. In the view of in-depth investigation on this topic, a 3-years project has been established to evaluate the use of multiple surveying techniques for the stability control of a complex historical structure. To this aim, TLS, total station (TS) and photogrammetry are being employed for stability control monitoring with finite element model (FEM) analysis applied to an historical building, Teatro Olimpico (Olympic Theatre), in Vicenza, Italy. The main goal of this work is to analyze and verify the stability over time of this kind of structure by applying FEM analysis to a highly detailed 3D model of the theater. To date, three consecutive surveys of the theater have been carried out with consumer digital-reflex camera Nikon D200, a Leica Laser Scanner (HDS 3000) and a Leica Total Station (TCR 705). The first survey comprised approximately 250 pictures to derive a global and complete 3D model of theater with an inexpensive measuring and modeling photogrammetry software (Photomodeler). In the second study, the historical structure was fully surveyed with a TLS, the Leica HDS 3000, to produce a complete 3D model. A set of scans of complex elements, such as the wood trompe l'oeil onstage scenery, statues, and fine trim, were acquired in this stage. This article presents the results from the repeated surveys and highlights the issues and difficulties related to the laser scanning and photogrammetry of an unusual and complex geometry such as the one provided by the Olympic Theater in Vicenza.
Vehicle longitudinal velocity is a corner stone to many important vehicular applications, especially the electronic stability control system, and needed to be theoretically estimated; in the ...meantime, it also requires more high performance of real time and accuracy. In this article, we propose a new method for the estimation of vehicle longitudinal velocity based on the wheel speed signals and evaluate their confidence levels with Takagi Sugeno Kang (TSK)-fuzzy model. First, according to the normal conditions and extreme conditions of experimental vehicles with the variation of the wheel speed in the electronic stability control intervention, the vehicle driving states can be divided into three kinds of working conditions: acceleration, deceleration, and sliding. Then, we consider whatever that may happen to the fuzzy rules in the automobile travel process. Although the quantities of fuzzy rules are many, the amount of computation is well controlled at the same time. Finally, the accuracy of longitudinal velocity estimation is verified through the real vehicle tests such as double-lane change course and slalom test. The results indicate that the longitudinal velocity does not show the wrong trend with the wheel speed signals changing rapidly under the extreme working conditions. The system has outstanding real-time performance and application.
Four wheel steering（4 WS） technology can effectively improve the vehicle handling stability and driving safety. In order to fully consider the influence of the rear wheel steering, the vehicle ...dynamics model of 4 WS vehicle, including the rear wheel steering by wire and two degrees of freedom vehicle model of 4 WS vehicle, is established in this paper. The desired yaw rate is obtained according to the variable transmission ratio strategy. The yaw rate tracking strategy is applied to 4 WS vehicle and rear wheel steering resistance moment is taken into account. Based on the robust control theory, H2/H∞ mixed robust controller design is carried to research the stability control of 4 WS vehicle. Finally, the closed-loop simulation added driver model based on preview theory is carried out. The simulation results indicate that the designed H2/H∞ mixed robust controller can achieve the stability control.
The automobile brake-by-wire (BBW) system, which is also called the electromechanical brake system, has become a promising vehicle braking control scheme that enables many new driver interfaces and ...enhanced performances without a mechanical or hydraulic backup. In this paper, we survey BBW control systems with focuses on fault tolerance design and vehicle braking control schemes. At first, the system architecture of BBW systems is described. Fault tolerance design is then discussed to meet the high requirements of reliability and safety of BBW systems. A widely used braking model and several braking control schemes are investigated. Although previous work focused on antilock and antislip braking controls on a single wheel basis, we present a whole-vehicle control scheme to enhance vehicle stability and safety. Simulations based on the whole-vehicle braking model validate a proposed fuzzy logic control scheme in the lateral and yaw stability controls of vehicles.
Most solenoid valves in use today require a magnetic coil to be continuously energized to maintain the magnetization of the magnetic body in order to operate. The problem is that if the power is ...still supplied, the power consumption will continue. In addition, problems such as shortening the lifespan of solenoid valve internal parts due to the increase in the internal temperature of the electronic stability control (ESC) due to the continuous heating of the magnetic coil, and malfunction due to instantaneous power failure may occur. In this study, we conducted a study on the permanent magnet traction control valve (TCV) for ESC that can minimize the unnecessary power consumption of electric vehicle batteries. For optimal permanent magnet design, polarity direction setting and permanent magnet specifications were studied through FE simulation. A permanent magnet TCV was fabricated and an electromagnetic force test was conducted to compare and evaluate it with the FE simulation result. By using a permanent magnet, it was possible to lower the initial current value for the TCV to drive, therefore, it was possible to develop a permanent magnet TCV that can minimize the unnecessary power consumption of electric vehicle batteries.
This study is targeted at the key state parameters of vehicle stability controllers, the controlled vehicle model, and the nonlinearity and uncertainty of external disturbance. An adaptive ...double-layer unscented Kalman filter (ADUKF) is used to compute the sideslip angle, and a vehicle stability control algorithm adaptive fuzzy radial basis function neural network sliding mode control (AFRBF-SMC) is proposed. Since the sideslip angle cannot be directly determined, a 7-degrees-of-freedom (DOF) nonlinear vehicle dynamic model is established and combined with ADUKF to estimate the sideslip angle. After that, a vehicle stability sliding mode controller is designed and used to trace the ideal values of the vehicle stability parameters. To handle the severe system vibration due to the large robustness coefficient in the sliding mode controller, we use a fuzzy radial basis function neural network (FRBFNN) algorithm to approximate the uncertain disturbance of the system. Then the adaptive rate of the system is solved using the Lyapunov algorithm, and the systemic stability and convergence of this algorithm are validated. Finally, the controlling algorithm is verified through joint simulation on MATLAB/Simulink-Carsim. ADUKF can estimate the sideslip angle with high precision. The AFRBF-SMC vehicle stability controller performs well with high precision and low vibration and can ensure the driving stability of vehicles.
The focus of this paper is on the nonparametric system design approach using a class of sampled regulators. Based on the review and evaluation of two stability design methods that were originally ...established for this class of sampled integral regulators, this paper has extended the stability theory and design algorithms in order to additionally consider generalized proportional-integral-derivative regulators. The link between the two original design methods has been revealed, based on which the whole benefit of the class of sampled regulator design methods can be embraced in a single framework. Furthermore, the suitability of the proposed design algorithms has been demonstrated in several power system applications.
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